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Y UNITED STATES PATENT OFFICE.

JAMES WV. EASTON, OF NEYV YORK, N. Y., ASSIGNOR TO P. MINTURN SMITH, OFPLAINFIELD, NEXV JERSEY, AND WILLIAM D. PERRY, OF BROOK- LYN, NE\V YORK.

COMMUTATOR FOR DYNAMOS.

SPECIFICATION forming part of Letters Patent No. 433,523, dated August5, 1890. Application filed November 16, 1889. Serial No. 330,593. (Nomodel.)

To all whom, it may concern:

Be it known that I, JAMEs WV. EAsTON, a subject of the Queen of GreatBritain, and a resident of the city of New York, in the county and Stateof New York, have invented certain new and useful Improvements inCommutators for Dynamo-Electric Machines, of which the following is afull, clear, and exact description, reference being had to theaccompanyin g drawings, forming part of this specification.

My invention relates to dynamo-electric machines and motors, andconsists in a novel form, construction, and arrangement of the sectionsof the commutator.

It consists, further, in the provision of means for preventingshort-circuiting between the sections of my improved commutator; and itconsists, further, in the novel construction, arrangement, andcombination of parts hereinafter more specifically described andclaimed.

In dynamo-electric machines the requisite pressure of the brushesagainst the commutator-cylinder produces sufficient friction to soonwear away the surface of the commutator, and in such machines asheretofore constructed a channel is speedily formed around the peripheryof the commutator where the brushes come in contact with it. The sidesof this channel are not straight and true,but are rounded or beveled,owing to the vibration of the shaft of the machine, and also to thevariation in the position of the brushes. The bottom of the channel alsobecomes uneven, and in consequence the contact between the brushes andthe commutator will be very intimate at some points in the width of thebrushes, while at others they will not be in contact at all. This causesan excessive amount of sparking and such a variation in the operation ofthe machine that the operation of the apparatus connected with it isoften seriously interfered with.

The object of my invention is to prevent the uneven wearing away of thecommutatorsections and to afford an even bearing for the extremities ofthe brushes until the com mutator is entirely worn out.

In the accompanying drawings, Figure 1 is a longitudinal sectionalviewof a commutator constructed in accordance with my improvements. Fig. 2is a transverse sectional view thereof on the line 2 2, Fig. 1. Fig. 3is a view in elevation of one of the sections of my improved commutator,and Fig. 4 is a corresponding view of one of the sections of acommutator of the ordinary construction showing the groove worn thereinby the brushes of the machine.

Similar letters of reference are used to indicate corresponding parts inall the views.

The sleeve or hub A is adapted to be suitably secured to the shaft ofthe machine, and

serves to support the commutator-sections B in any usual manner. Asshown, the inner end of the sleeve A is provided with the undercutflange a, and the outer end of the sleeve is screw-threaded to receivethe nut O, which bears against the undercut collar D, which is adaptedto slide along the sleeve A. The commutator-sections are suitablyinsulated from the sleeve and collar, and also from each other, bystrips or rings of insulating material E. Then the commutator-sectionsare placed in position, the nut O is screwed up tightly against thecollar D, which in turn exerts sufficient pressure against the sectionsto hold them firmly in place.

The commutator-sections B consist, preferably, of thin sections ofcopper, and are preferably provided with the projecting arm I) for theattachment of the armature-coils. They are advantageously madeconsiderably deeper than is ordinarily done, so that they will projectout beyond the outer surface of the collar D. Each of the sections B isprovided with a slot 1) at a distance from the outer edge of the sectionequal to the width of the brushes to be used. WVhen the sections are inposition, these slots 1) form a continuous channel around the peripheryof the commutator, and the depth of the slots is such that the channelwill extend down to the point to which the sections can be worn beforebeing discarded. These slots maybe formed in the sections in anydesirable way. For instance, they may be formed separately before thesections are mounted on the shaft, or they may be cut simultaneouslyafter the sections are in position, care being taken that the edges ofthe channel are even and at right angles to the axis of revolution. Asthus constructed, an even wearing or contact surface is provided for thecommutator of the exact width of the brushes, and this surface is evenlymaintained until the sections are Worn down to the depth of the channelor groove, when the sections may be replaced by new ones.

In order to prevent the possibility of the short circuiting of thecommutator, which might ensue if the groove were to become filled withdust, dirt, and abraded metal, I fill the groove with any suitableinsulating material 12 preferably such as can be readily removed inlayers as the contact-surface of the commutatoris Worn away. I prefer tofill the groove in the following manner, although it is to be understoodthat I do not limit myself thereto: A layer of varnish or glue is firstputinto the bottom of the groove and then a layer of flaxthread-such asis used by harness or shoemakers-is wound therein. Thisis then coatedwith the varnish or glue and another layer of thread is wound in, and soon until the groove is filled. The glue or varnish serves to fill up allcracks and crevices, and the thread prevents it from falling out orcracking if it becomes heated. The thread is disposed in even layers andcan be easily cut through with a knife, thus permitting layer afterlayer to be readily removed as the contact-surface of the commutator isWorn down. As stated, however, any other suitable insulating materialmay be used, and it may be inserted in the groove in any desirablemanner.

I use the Words contactsurface in the claims to designate thatparticular portion of the commutator against which the brushes areadapted to bear.

Having thus described my invention, What I claim as new, and desire tosecure by Letters Patent, is-

1. A commutator provided with a groove or channel to limit the width ofits contact-surface, such groove being filled with insulating material,substantially as and for the purposes set forth.

2. A commutator provided withagroove or channel to limit the width ofits contact-surface, such groove being filled with insulating materialin separable layers, substantially as and for the purposes set forth.

JAMES WV. EASTON.

Witnesses:

S. G. METoALF, WILLIAM Lnvn.

